From owner-freebsd-net@FreeBSD.ORG Sat Jul 27 20:49:36 2013 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 0CCEA452 for ; Sat, 27 Jul 2013 20:49:36 +0000 (UTC) (envelope-from zbeeble@gmail.com) Received: from mail-vc0-x233.google.com (mail-vc0-x233.google.com [IPv6:2607:f8b0:400c:c03::233]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id C2DB5246C for ; Sat, 27 Jul 2013 20:49:35 +0000 (UTC) Received: by mail-vc0-f179.google.com with SMTP id ht10so1268056vcb.24 for ; Sat, 27 Jul 2013 13:49:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:content-type; bh=+GG5LsLPu8s6xuqXkJheeyKyxgiGzfnAcJe5ktfRvy4=; b=ZpY0L151MKEpMtjaEkIN34w18pCL+/jw13rA7MedOiEPmU+PDlC7+Zl6S50XwuzsxR OZnhDvq8rsW9INuQI4+6utOTtTS7YBbmIv0JGZcBOOjxrk6hi3+83hKcew/MgMvlUabJ csseuSkpHokEfQU+wD68S9DaZkIeYZEneVM575i43BZ2Q+KM+ZRL8Uu9BMm6j0yIzR3V A/tQ9E97WaNU817fKxe9xWWtcbEMiJ6UIJ+guRtYE2C5tEAX4dH88s9OU5BEbnVxsLAV doGtHTmoA13KMM84YLkxptaJx1e3FTDuNjZcWIxOTMYRRdgMJqfEHdG0FNrRdS8Mws3A Ys5g== MIME-Version: 1.0 X-Received: by 10.58.67.9 with SMTP id j9mr23520705vet.22.1374958174869; Sat, 27 Jul 2013 13:49:34 -0700 (PDT) Received: by 10.221.22.199 with HTTP; Sat, 27 Jul 2013 13:49:34 -0700 (PDT) Date: Sat, 27 Jul 2013 16:49:34 -0400 Message-ID: Subject: Please implement patch in PR180893 From: Zaphod Beeblebrox To: FreeBSD Net Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 27 Jul 2013 20:49:36 -0000 I'd like to advocate implementing http://www.freebsd.org/cgi/query-pr.cgi?pr=180893 Quoting the PR: Some errant network equipment (including the simulation of a network by VMware, as an example) will reflect back multicast packets to the sender. This breaks protocols such as DAD and makes IPv6 nearly impossible to use on these networks. Now, the argument could be made to fix these network elements, but there is an elegant solution that improves the quality of FreeBSD: To refuse packets that have a source ethernet address of the receiving interface. If you consider this notion, you can quickly and easily accept that an interface should never "receive" a packet from it's own MAC address. This behaviour mirrors Linux behavior and I assume Windows behavior. I won't claim to be experienced in kernel matters, but I chose the location for this modification to allow BPF to "see" the packets (for network diagnosis). This test, however, could be moved within this function or even given a sysctl knob.